Problem: Metric with "tilde" not displayed

The Icinga GraphiteWriter has written perfdata with a tilde in it name. Icingaweb is not able to display this graph, because the tilde char gets replaced with an _. And with the replaced char, graphite is of course not able to find the metric.

Example on disk:

/var/lib/graphite/whisper/icinga2/server1/services/idrac-hardware-coolingdevice/checkhardware/perfdata/test~component/
/var/lib/graphite/whisper/icinga2/server1/services/idrac-hardware-coolingdevice/checkhardware/perfdata/test~component/fan
/var/lib/graphite/whisper/icinga2/server1/services/idrac-hardware-coolingdevice/checkhardware/perfdata/test~component/fan/speed
/var/lib/graphite/whisper/icinga2/server1/services/idrac-hardware-coolingdevice/checkhardware/perfdata/test~component/fan/speed/value.wsp

In the web interface the graph is then displayed with the "broken" image.
Example Link of the webinterface (note the "tilde" in the string)
https://icinga2/icingaweb2/graphite/graph/service?host.name=server1&service.name=idrac-hardware-coolingdevice&service.check_command=checkhardware&multi1=test~component&multi2=fan&multi3=speed&default_template=multi3-service&start=-86400&end=&width=350&height=200&legend=1

This result to this query in the apache graphite access log:
127.0.0.1 - - [30/Apr/2025:09:07:39 +0000] "GET /metrics/expand?query=icinga2.server1.services.idrac-hardware-coolingdevice.checkhardware.perfdata.test_component.fan.speed.value HTTP/1.1" 200 198 "-" "icingaweb2-module-graphite"
As you can see here tilde got replaced with an underscore.

After a bit debugging I have added the tilde char in the file library/Graphite/Graphing/MetricsQuery.php Line 217 to the preg_replace.
The result is, that the graphs are now display correctly.

I am not sure if this cause other problems, and if it was intentional to not include this char here.
But in my tests so far everything looks good.

Start in library/Graphite/Graphing/MetricsQuery.php around line 217 and inspect how metric characters are transformed by the preg_replace. Reproduce the query for the documented test~component metric and verify that the generated Graphite request preserves the tilde and the graph displays correctly. Confirm that the character handling does not break other metric names.